Circuit breaker



June 10,- 1930. c. V s c E 1,763,202

CIRCUIT BREAKER Filed April 2, 1927 WITNESSES: INVENTOR 2/ MW Raswefl C. Var? Sick/e JJM BY Ai'TORNEY Patented June 10, 1930 UNITED STATES PATENT OFFICE ROSWELL C. VAN SICKLE, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA CIRCUIT BREAKER Application filed April 2,

My invention relates to electrical circuit interrupting devices and especially to electrical closing mechanism therefor.

One object of my invention is to provide a circuit interrupter that shall have a plurality of closing mechanisms.

Another object of my invention is to employ the electrical current incident to an overload or short-circuit condition to assist the main closing mechanism to operate the circuit interrupter against the overload or short-circuit condition.

A further object of my invention is to provide a contactor that operates after the circuit interrupter has been closed, to shunt out the electrical conductor supplying the currents to the auxiliary closing mechanism, to prevent the losses that would otherwise occur when operating under normal conditions and to prevent the auxiliary closing mechanism from holding the contacts closed when they should be free to open.

The closing mechanism of a circuit interrupter is so designed that a minimum voltage may operate the interrupter under normal conditions. When a condition other than normal is present in the circuit, such as an overload or short circuit condition, such resistance may be offered at the contact members as to prevent the bridging member from being completely closed. The bridging member coming into engagement with the contact members, forms a path of U-shape and, when an electrical current is flowing in a conductor of this shape, the flux thereabout, crowding on the inner side of the bottom portions of the contact members, reacts against the bridging member and resists its closing. Additional resistance is offered by the parallel-type brush and the finger contacts. A current of like polarity flowing in parallel paths; inherent in either type of contacts, will cause the members to be drawn together, resulting in a resistance being offered to their separation, which separation is necessary to the complete closing of the circuit interrupter.

.The resistance due to the crowding of the flux in the U-shape conductor and to the separation of the parallel-path contacts may 1927. Serial No. 180,464.

become very appreciable when a large current is flowing, such as one flowing when a condition of overload or short circuit is present. Under these conditions, upon closing the circuit interrupter by means of the present closing mechanism, the resistance at the contact members may be so great as to hold the bridging member ajar, whereby damage to the contact member by the ensuing arc will result.

According to my invention, I provide an auxiliary closing mechanism that is operated by the current incident to the shortcircuit condition, the power of which closing mechanism will vary with the resistance oilered at the contactmember, as above described, so that the force exerted by the additional closing mechanism will always be suilicicnt to assist the main closing member in operatingthe circuit interrupter. The auxiliary closing mechanismmay be connected directly in series withthe main electrical circuit, or a current transformer may be employed and the auxiliary closing mechanism be operated therefrom. In order to prevent the losses that would occur in the auxiliary closing mechanism, when the circuit interrupter is in the closed position, an electrically actuated contactor is used to short circuit it, or, alternatively, to short circuit the current transformer when such is used, and thus effectively shunt it outof the main electrical circuit. This arrangement also prevents an overload or short-circuit condition from holding the current interrupter closed when the prevailing condition should cause it to be tripped.

In practicing my invention, I am, there fore, ableto insure that the circuit-interrupter shall be completely closed, even though the condition of overload or short circuit exists in the main circuit.

Referring to the accompanying drawing:

Figure 1 is a schematic view of apparatus embodying my invention and having a coil connected in series with the main electrical circuit to operate the extra closing mechanism.

Fig. 2 is a simliar view of apparatus embodying my invention and having current transformers, in a three-wire alternatingcurrent circuit, to operate the extra closing mechanisms.

My invention comprises, in general, a circuit interrupter 1 having a main closing mechanism assisted by an auxiliary closing mechanism 3. The assistance offered by the auxiliary closing mechanism will vary as the current conditions of a main electrical circuit change; that is, a short-circuit condition existing in the main electrical circuit l will resist movement of the bridging members 5 to circuit-closing positions, necessitating the employment of an auxiliary closing mechanism that will increase in strength with an increase of current, thereby ensuring the closing of the circuit interrupter when a short-circuit condition exists in the main circuit.

In the accompanying drawing, the circuit interrupter l, hav'ag bridging memhers 5 to close the main electric circuit a, has an operating mechanism 6 that is actuated by the closing mechanism 2, with slight assistance from the auxiliary closing mechanism 3 when a n rmal condition exists in the main electric circuit l. Thus, the main closing mechanism 2 is always assisted by the auxiliary closing mechanism 3 acting through the current coil 7, but the arrangement is such that, if an overload or short-circuit condition happens to exist in the main electric circuit 4, just at the instant the contacts touch each other to complete the main circuit, this assistance is materially increased.

In Fig. 2, the main closing mechanism 2 is assisted by similar auxiliary closing mechanisms 3 that have their coils 7 and 8 energized from current transformers 9 when a condition of overload or short circuit happens to exist at the instant the circuit breaker is being closed in any pair of wires in the three-wire alternating-current main electric circuit 4L.

As illustrated in each of Figs. 1 and 2, a control switch 12 establishes an electrical circuit for the main closing mechanism 2 to connect it to the electrical control circuit 13 in order to close the circuit interrupter 1. The coil of the closing mechanism 2 is so designed that, with the minimum closing voltage impressed thereon, it is just able to close the circuit interrupter 1. This is necessary in order to prevent the moving parts from slamming and being damaged when an excess voltage is present in the electrical control circuit 13. With the last movement in the closing cycle of the circuit interrupter l, the auxiliary contactor 15 is operated to make an electric circuit with the operating solenoid of the contactors 1a, closing its contacts and shunting the circuit to the coil 7 or the coil 8. This cuts off the current to the auxiliary closing mechanisms 3, thus preventing the losses that would occur therein when the circuit interrupter is operating under normal line condition and also preventing an excess current that would otherwise be present in the auxiliary closing mechanism 3 from holding the circuit interrupter 1 closed against a condition that should properly open it.

Assuming the circuit interrupter to be in the closed position, as shown in the drawing, the closing mechanisms 2 and 3 will be deenergized, the former by the opening of control switch 12, the latter by the closing of the contactor 14.. In the open position, the circuit interrupter 1 may be closed by the functioning of the closing mechanism 2 until a circuit is established by the contact members 5, after which it will be assisted by the auxiliary closing mechanisms 3, as current will then be flowing in the coil 7 or in the coil 8 in the normal manner. In case of a condition of overload or short circuit in a pair of the main electric conductors a, the additional current incident thereto will cause a greater energization of auxil iary closing mechanism 3. This will materially assist the main closing mechanism 2 in overcoming the additional forces incident to the overload or short-circuit conditions aforesaid.

After the circuit interrupter 1 has been closed, the contactor l4 automatically short circuits the coil 7 or the coil 8 of the auxiliary closing mechanism 3, as explained hereinbefore, and eliminates the current normally flowing in the main electric circuit 4 from the coil 7 or the coil 8 of the auxiliary closing mechanism 6, thus also eliminating the losses that would occur therefrom and preventing the auxiliary closing mechanism 3 from holding the bridging member 5 closed when it should be left free to open.

Accordingly, my invention obviates the possibility of damage that might occur to the contact members of a circuit interrupter because of its incomplete operation against the forces present therein when an overload or short-circuit condition exists in the main electric circuit. If the overload or short circuit condition is of small magnitude, the

force in the auxiliary closing mechanism incident to its presence will be correspondingly small but will be suflicient to assist the main closing mechanism to operate the contacts against the resistance at the contact members.

The force in the auxiliary closing mechanism will be correspondingly greater if the overload or short-circuit condition is of greater value, and its assistance will be sufficient to overcome the greater resulting resistance at the contact members. It, therefore follows, that, upon any condition of overload or short circuit, my invention will enable the circuit interrupter to be completely closed, thereby obviating the possi bility of damaging the contact members or the circuit interrupter itself.

It is to be understood that such changes in the form, arrangement and connection of the component parts of my invention may be made as shall fall within the scope of the appended claims.

I claim as my invention:

1. The combination, in a circuit interrupter connected in an electrical circuit, of a closing means therefor, and electro-responsive closing means that operates in conjunction with the said closing means when a condition of overload or short-circuit exists in the main electrical circuit.

2. The combination, in a circuit interrupter connected in an electrical circuit, of a closing means therefor, and a plurality of electro-responsive closing means that operate in conjunction with the said closing means when a condition of overload or short-circuit exists in the main electrical circuit.

3. The combination, in a circuit interrupter connected in an electrical circuit, of an electrical closing means therefor, and electro-responsive means in series relation to the main electrical circuit so arranged that a condition of overload or short circuit will energize the electro-responsive means and assist the closing means to close the circuit interrupter against the short-circuit condition in the main electrical circuit.

4. The combination, in a circuit interrupter connected in an electrical circuit, of an electrical closing means therefor, and electro-responsive means having a coil connected to a current transformer that is so disposed in the main electrical circuit that a condition of overload or short circuit will energize the electro-respc-nsive means and assist the closing means to close the circuit interrupter.

5. The combination, in a circuit interrupter connected in an electrical circuit, of an electrical closing means therefor, and elec-- tro-responsive means having a plurality of coils each connected to one of a plurality of current transformers so disposed on the phases of an electrical circuit, that a condi-- tion of overload or short circuit in any phase will energize the electro-responsive means and assist the closing means to close the circuit interrupter.

6. The combination, in a circuit interrupter connected in an electrical circuit, of a plurality of solenoid operating mechanisms, and a plurality of current transformers disposed in the electrical circuits, each so connected to a solenoid operating mechanism that the current due to a condition of overload or short circuit will be employed to assist in closing the circuit interrupter.

7. The combination, in a circuit interrupter connected in an electrical circuit, of a closing means therefor, electro-responsive means for assisting the closing means and employing the current from the main electrical circuit, and. short circuiting means for the electromesponsive means, disconnecting the main electrical circuit therefrom after the circuit interrupter is closed.

8. The combination, in a circuit interrupter connected in an electrical circuit, of an electrical closing means therefor, electroresponsive means adapted to assist the closing means having a coil connected to a current transformer that is disposed in the main electrical "circuit, and short circuiting means for shunting the connections from the current transformer to the electro-re-- sponsive means.

9. The combination, in. a circuit interrupterv connected in an electrical circuit, of an electrical closing means therefor, electroresponsive means adapted to assist the closing means having a coil connected to a c rrent transformer that is disposed in the main electrical circuit, and short circuiting means for shunting the current transformer from the main electrical circuit.

10. The combination, in a circuit inter rupter connected in an electrical circuit, of a closing means therefor, electro-responsive means that operate in conjunction with the said closing means with a force varying with the current flowing in the main electrical circuit, and means for short circuiting the electro-responsive means from the main electrical circuit after the circuit interrupter has been closed.

11. The combination, in a circuit interrupter connected in an electrical circuit, of a closing means therefor, a plurality of electro-responsive means that operate in conjunction with the said closing means with a force which varies with the current flowing in the main electrical circuit, and a plurality of means for short-circuiting the plurality of electro-responsive means from the main electrical circuit after the circuit interrupter has been closed.

12. The combination in a circuit interrupter connected in an electrical circuit, of a closing means therefor and electro-responsive means adapted to operate in conjunction with the said closing means with a force varying with the current flowing in the said electrical circuit.

13. The combination in a circuit interrupter connected in an electrical circuit, of a closing means therefor and a plurality of electro-responsive means adapted to operate in conjunction with the said closing means with a force varying directly with the current in the said electrical circuit.

14. The combination, in a circuit interrupter connected in an electrical circuit of a plurality of solenoid operating mechanisms one of which is normally employed to close the circuit interrupter, a current transformer so disposed in the main electrical circ it and connected to another of the solenoid operating mechanisms that the current due to a predetermined circuit condiion may be employed to assist in closing the circuit interrupter.

15. The combination with a circuit interrupter connected in a main circuit and having contact members operable to complete ii said circuit, of a motor means for actua the contacts to closed position and a second means energized by the increased current in the main circuit to assist the said motor to close e contacts against the innreased repellel' a force or"- the excess current.

lo. The combination wi h a circuit interrupter connected in a main circuit and having contact members operable to complete the said circuit, of a motor means for actuating the contacts to closed position and a second means energized by the increased current in the main circuit to assist the said motor to close the contacts with a force proportional to the increased repellent force :t the contact members produced by the said increased current in the main circuit.

In testimony whereof I have hereunto subscribed my name this 30th day of March,

ROSVELL C. VAN SIOKLE. 

